КООРДИНАЦИОННАЯ ХИМИЯ, 2007, том 33, № 6, с. 427-431
УДК 541.49
NEW GLYOXIMES DERIVATIVES AND THEIR TRANSITION
METAL COMPLEXES
© 2007 B. Yildirim, E. Ozcan, and P. Deveci
Department of Chemistry, Faculty of Arts and Sciences, Selcuk University, 42031 Konya, Turkey
Received June 9, 2006
Two new vic-dioxime ligands and their complexes with Co+2, Ni+2, Cu+2, Cd+2, and Zn+2 ions were synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichloroglyoxime to give 3,4-methylenedioxaphenylaminoglyoxime (H2LX) and N-(4-methylbenzyl)aminoglyoxime (H2L2) ligands. Structures of the ligands and their complexes are proposed based on elemental analyses, IR, UV-Vis, and XH NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA).
INTRODUCTION
v/c-Dioximes and their complexes constitute an important class of compounds having versatile reactivities [1]. Oxime metal chelates are biologically active [2] and are reported to posses semiconducting properties [3, 4]. The substitution pattern of the v/c-dioxime moiety affects the structure and stability of the complex [5]. Compounds containing the 1,3-dioxalane group are used as solvents, additive compounds, and corrosion retardants, while polymers containing 1,3-dioxalane groups exhibit semiconducting behavior [6, 7].
v/c-Dioximes have a high tendency to form isomers. When the molecule is formally symmetrical, three forms are possible: syn-, ant/-, and amph/--structures, usually the stability order of these forms: ant/- > amph/- > syn-config-uration, but there are some exceptions. The dioximes ant/-isomers are responsible for the formation of brightly colored chelate derivatives with nickel and other transition metal ions [8-10]. Especially, the ant/-form gives blood-red complexes with nickel ions.
This paper describes the synthesis of novel soluble vic-dioxime ligands and their complexes with nickel(II), cop-per(II), cobalt(II), cadmium(II), and zinc(II). As far as we know, this is the first report on these ligands.
EXPERIMENTAL
The preparation of ant/'-chloroglyoxime has been described previously [11]. All the reagents used were purchased from Merck, Fluka, or Sigma and were chemically pure.
Elemental analyses (C, H, N) were performed on a LECO-932 CHNSO apparatus. IR spectra were recorded on a Perkin Elmer Model 1605 FT-IR spectrophotometer from KBr pellets. XH NMR spectra were recorded on a Bruker GmbH Dpx-400MHz high-performance digital FT-NMR spectrometers in DMSO-d6. Magnetic moments of the complexes were measured using a Sherwood scien-
tific model MX1 Gouy magnetic susceptibility balance at room temperature. TGA curves were recorded on a Shima-deu TG-50 thermobalance.
Synthesis of 3,4-methylenedioxaphenylaminogly-oxime ligand (H2L1). A solution of 3,4-methylenedioxaaniline (1.37 g, 0.01 mol) in CCl4 (30 ml) was added to a solution of triethylamine (0.01 mol) in CCl4 (30 ml). This mixture was cooled from -5 to -10°C, and a solution of of ant/'-chloroglyoxime (1.23 g, 0.01 mol) in di-ethylether (30 ml) was added with continuous stirring. Addition of an ant/-chloroglyoxime solution was carried out over 1 h. After the mixture was stirred for 1 h more, the temperature raised to 5°C. The precipitated triethy-lamine salt was filtered off, and the filtrate was evaporated to remove the solvent. The oily product was dissolved in CHCl3 and recrystallized from a mixture of chloro-form-n-hexane (1 : 5). The obtained product was filtered off, washed with diethylether several times, and dried in vacuum. The purified ligand is soluble in common solvents, such as DMSO, DMF, and dioxane, and insoluble in diethyl ether, ethanol, and n-hexane. Characteristic XH NMR peaks (DMSO-d6, 400 mHz), 5, ppm: 6.12 (s., 2H, -O-CH2O-), 7.52 (s., 1H, H-C=N), 6.14 (s., 1H, N-H), 10.71-11.88 (s., 2H, N-OH), 7.11-7.80 (m., 3H, Ar-H).
Synthesis of complexes [Ni(H2L1)2] (I), [Co(H2L1)2(H2O)2] (II), and [Cu(H2L1)2] (III). The ligand (2.23 g, 1 mmol) was dissolved in absolute methanol (10 ml), and a solution of 0.5 mmol of the appropriate metal salt (CoCI2 ■ 6H2O (0.12 g), NiCI2 ■ 6H2O (0.12 g), or CuCl2 ■ 2H2O (0.09 g)) in absolute methanol (5ml) was added dropwise to the ligand solution with continuous stirring. The color of the solution immediately turned dark brown for Co(II), tile red for Ni(II), and green for Cu(II). The pH of the solution, which decreased to 3.5, was adjusted to 5-6 by the addition of a 1% triethylamine solution in ethanol. Each mixture was stirred for more than 1 h at 30°C. The precipitated complexes were kept on a water bath for 35 min at 40°C and filtered off, and the
precipitate was washed with water, ethanol, and diethyl-ether. The complexes are soluble in DMSO, DMF, and THF and insoluble in diethylether, water, ethanol, and n-hexane. Characteristic XH NMR peaks for (H2Lx)2Ni (DMSO-d6, 400 mHz), 5, ppm: 6.10 (s., 4H, -O-CH2-O), 7.21 (s., 2H, H-C=N), 6.08 (s., 2H, N-H), 14.89 (s., 2H, O-H-O), 6.91-7.2 (m., 6H, Ar-H).
Synthesis of complex [Cd(H2L1)Cl] • H2O (IV). The
ligand (2.23 g, 1 mmol) was dissolved in absolute methanol (10 ml). A solution of metal salt CdCl2 ■ H2O (0.21 g, 1 mmol) in absolute methanol (10 ml) was added drop-wise to the ligand solution with continuous stirring. The apparent pH of the solutions was adjusted to 5-5.5 by the addition of a 1% triethylamine solution in ethanol. The mixture was further stirred on a water bath at 50°C for 2 h in order to complete precipitation. The precipitate was filtered off, washed with diethyl ether, and dried in vacuum. The complex is soluble in THF, DMF, and DMSO and insoluble in diethylether, ethanol, and n-hexane.
Synthesis of N-(4-methylbenzyl)aminoglyoxime ligand (H2L2). 4-methylbenzylamine (2 x 10-2 mol) was dissolved in ethanol (5 ml). A solution containing anti-chloroglyoxime (1.23 g, 1 x 10-2 mol) in ethanol (5 ml) was added slowly at room temperature with constant stirring. The mixture was stirred for 2 h.The pH of the mixture was about 7.0-7.5. Its volume was then doubled by adding distilled water. The resulting white precipitate was filtered off, washed with cold water, dried, and crystallized from a water-ethanol (1 : 3) mixture. The title compound is soluble in diethyl ether, DMF, DMSO, dioxane, and ethanol and less soluble in water and chloroform. Characteristic 1H NMR peaks (DMSO-d6, 400 mHz), 5, ppm: 2.10 (s., 3H, -CH3), 4.51 (s., 2H, -CH2), 7.14 (s., 1H, H-C=N), 5.94 (s., 1H, N-H), 10.31-11.32 (s., 2H, N-H), 7.00-7.21 (m., 4H).
Synthesis of complexes [Ni(H2L2)2] (V), [Co(H2L2)2(H2O)2] (VI). A solution of metal salt NiCI2 ■ 6H2O (1.189 g, 0.5 mmol), CoCl2 ■ 6H2O (1.19 g, 0.5 mmol) dissolved in EtOH (5 ml) was added to a stirred solution of H2L2 (2.07, 1 mmol) dissolved in EtOH (5 ml). The mixture was heated to 60°C, and 1 M NaOH solution in ethanol was added dropwise. The reaction was allowed to continue for 3 h at 60°C. The mixture was allowed to stand for 1day at room temperature. The precipitated complexes were filtered off, washed with EtOH and dried in vacuum at 60°C. Characteristic XH NMR peaks for (H2L2)2Ni (DMSO-d6, 400 mHz), 5, ppm: 2.23 (s., 6H, -CH3), 4.52 (s., 4H, -CH2), 7.03 (s., 2H, H-C=N), 5.62 (s., 2H, N-H), 14.80 (s., 2H, O-H-O), 6.90-7.21 (m., 6H, Ar-H)
Synthesis of complexes [Cd(H2L2)Cl] • H2O (VII), and [Zn(H2L2)Cl] • H2O (VIII). The ligand H2L2 (2.07 g, 1 mmol) was dissolved in absolute ethanol (15 ml). Solutions of metal salts CdCI2 ■ H2O (2.03 g, 1 mmol), ZnCI2
(1.38 g, 1 mmol) in absolute ethanol (15 ml) were added dropwise to a ligand solution with continuous stirring at 60°C. The color of the solutions immediately changed. The reaction mixture was stirred at this temperature for 3 h and filtered, and the precipitate was washed with water, etha-nol, and diethyl ether and dried in vacuum at 60°C.
RESULTS AND DISCUSSION
3,4-Methylenedioxaphenylaminoglyoxime (H2LX) and N-(4-methylbenzyl)aminoglyoxime (H2L2) were obtained from the anti-chloroglyoxime and 3,4-methylenedioxa-aniline or 4-methylbenzylamine:
OH,
(H2L2)
H'
C=N I
C=NV
,OH
"OH
The ligand and their complexes were characterized by elemental analyses, IR, XH NMR, UV-Vis spectroscopy, thermogravimetric analyses (TGA), differential thermal analysis (DTA), and magnetic susceptibility.
The elemental analyses of H2LX and its Co(II), Cd(II), Ni(II), and Cu(II) complexes are in agreement with theoretical expectations (Table 1). The analytical and physical data show a metal : ligand ratio of 1 : 2 for Ni(II), Co(II), and Cu(II). The complexation of H2LX with Cd(II) gives a product with a 1 : 1 metal : ligand ratio. The reaction of the ligand and Ni(II), Co(II), Cu(II), and Cd(II) salts yield complexes corresponding to the general formulas [Ni(H2Lx)2], [Co(H2Lx)2(H2O)2], [Cu(H2Lx)2], and [Cd(H2Lx)Cl] ■ H2O.
The elemental analyses of H2L2 and its Co(II), Ni(II), Cd(II), and Zn(II) complexes are in agreement with theoretical expectations (Table 1). The analytical and physical data show a metal : ligand ratio of 1 : 2 for Ni(II) and Co(II). The complexation reaction of H2L2 with Cd(II) and Zn(II) gives a product with a 1 : 1 metal : ligand ratio. The reaction of the ligand and Ni(II), Co(II), Cd(II), and Zn(II) salts yield complexes corresponding to the general formulas [Ni(H2L2)2], [Co(H2L2)2(H2O)2], [Cd(H2L2)Cl] ■ H2O, [Zn(H2L2)Cl] ■ H2O.
In the IR spectrum of the ligands, the most characteristic peaks appear around 960-970 v(N-O), 1610-1640 v(C=N), 3370-3420 v(N-H ), and 3368-3398 cm-1
Table 1. Elemental analysis data for the H2L\ H2L2 and compounds I-VIII and some of their physical properties
Compound Empirical formula Color M.p., °C Yield, % Content (found/calcd), %
C H N
H2L1 [C9H9N3O4] White 169 55 49.10/48.43 3.97/4.03 18.81/18.83
[Ni^L1^] (I) [Ci8Hi6N6O8Ni] Red 282 80 43.09/42.96 3.13/3.18 16.64/16.70
[Co(H2L1)2(H2O)2] (II) [Ci8H2oN6OioCo] Brown 184* 45 40.16/40.08 3.65/3.71 15.43/15.58
[Cu(H2L1)2] (III) [Ci8Hi6N6O8Cu] B
Для дальнейшего прочтения статьи необходимо приобрести полный текст. Статьи высылаются в формате PDF на указанную при оплате почту. Время доставки составляет менее 10 минут. Стоимость одной статьи — 150 рублей.